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Math Help - Clock Problem

  1. #1
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    Clock Problem

    The minute hand and hour hand form a right angle at 3:00. How long after till they form a right angle again? Give the answer to the nearest second.
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  2. #2
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    Quote Originally Posted by needhelp_21 View Post
    The minute hand and hour hand form a right angle at 3:00. How long after till they form a right angle again? Give the answer to the nearest second.
    let the 12 position be \theta = 0

    t = time in seconds after 3 o'clock

    position of the minute hand ...

    \theta_m = \frac{1}{10} \frac{deg}{sec} \cdot t

    hour hand ...

    \theta_h = 90 + \frac{1}{120} \frac{deg}{sec} \cdot t

    the next time they are 90 degrees apart, the minute hand will have passes the hour hand ...

    90 = \frac{1}{10} \cdot t - \left(90 + \frac{1}{120} \cdot t \right)

    solve for t in seconds
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  3. #3
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    I'm confused. How do I solve for t in seconds from that equation?
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  4. #4
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    Quote Originally Posted by needhelp_21 View Post
    I'm confused. How do I solve for t in seconds from that equation?
    algebra?
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